Why BSA Bottom Bracket is much durable than pressfit BB?

[madonna]

Hi Guys,

Can you help me to understand why the classic BSA BB is so much better than the fancy pressfit BB? Seems to me that most pressfit BB had the issues with creaking nose and premature bearing wear. Even colnago has gone into pressfit BB for C60 in favor of a stiffer bottom bracket however pinarello still stick to the BSA BB.

[fa63]

Because the BSA bottom brackets are held in by nice threads, while the press-fit ones are essentially held in by friction

Also, the Colnago BB is a bit of a hybrid between a threaded and press-fit bottom bracket. Not sure though if it is best of both worlds, or a master of none.

[Calnago]

Pressfit BB's are very difficult, it would seem, for manufacturers to get right. The tolerances have to very tight and accurate for a good PF system to work. Unfortunately, the tolerances in the industry to date are anything but, so they've come up with a mushy plastic like cups of delrin, nylon or whatever to be able to squish these into shells of questionable tolerance and hope they will deform enough to fit. Quite frankly, it's a mess. They can work for sure, but the install has to be done right, and often with loctite and associated primers to get them to stay put. Grease is not a good solution here as it just masks the creaking for while as the bottom bracket cups still move around in the shell. Bearings often wear much quicker due to misalignment of cups etc and poor installs.
Colnago's solution is arguably the best out there (aside from threaded which is still the best) that I'm aware of but is still a kind of fix to a problem that should never have been in the first place. Their Threadfit system essentially incorporates threaded alloy sleeves into the bb shell. They are actually replaceable should they ever wear enough to need it. Contrast that to a cup that moves around in a carbon shell and has to be removed and replaced by pounding out and pressing in and eventually that expensive frame becomes a throw away item.
The Colnago bb essentially creates a nice round interface for Pressfit systems to be pressed into. Great! So now we've got in essence double the layers of interfaces that we really need, but at least they're within tolerance. You still need to use various adapters depending on the crank you want to use. That's the short version.
Now go back to threaded BSA bottom brackets and you have 1) simplicity; 2) easy installs; 3) no creaking, cuz it's all very solid as long as the BB is properly faced etc. But it's not cost effective for manufacturers to produce especially with the molded frames today so they kind of do the best they can and pass the buck to others. BSA threaded is still the most reliable trouble free system out there. Colnagos Threadfit system is merely an attempt to make the best of a bad situation, but still not as nice as the old BSA threaded.
Then you have Pinarello, which is still using a threaded BB, but it's not BSA. It's Italian threaded for God sake. Even Colnago abandoned the Italian threads in favor of English threads back in 2008. In the old days, if the bottom bracket cups weren't tight enough, the way in which the bearings turned could "unscrew" the bottom bracket of an Italian threaded bike. Happened to me during a cross country trip once and the damn thing kept loosening up until I could get to a town where they had a proper tool to get it tightened down again. But with English threads that would never have happened in the first place.
So that's a real quick version of the BB saga, without going into the whole multiple "Standards" thing.
Have fun.

[fromtrektocolnago]

The new standards are better because they allows the manufacturer to build a bike more quickly and cheaply. it's not better for the bike owner or the local bike shop that might have to deal with the infamous service issues. I'll take threaded BB any day of the week.

[madonna]

I had a LOOK 695 and I am tempted to switch to a BSA BB with an adapter. Having looked into the details of the so call BB65 I am totally disappointed. There is innovation for the sake of showing off what they can do but neglected the reliability and ease of maintenance of the BB. In my own opinion I do not see BB65 technology as a performance upgrade. The bearing itself is quite smooth but the bearing dust cap and others cause excessive friction which totally lost out to my dura ace BSA BB. And I also discovered that the waterproofing of most pressfit BB is quite poor.

[GT56]

I had a LOOK 695 and I am tempted to switch to a BSA BB with an adapter. Having looked into the details of the so call BB65 I am totally disappointed. There is innovation for the sake of showing off what they can do but neglected the reliability and ease of maintenance of the BB. In my own opinion I do not see BB65 technology as a performance upgrade. The bearing itself is quite smooth but the bearing dust cap and others cause excessive friction which totally lost out to my dura ace BSA BB. And I also discovered that the waterproofing of most pressfit BB is quite poor.

the look bb65 system is more about their full carbon, one piece, crankset than about the bearing being larger or the threadless frame being lighter

the crankset is a very exiting demonstration of what can be achieved with carbon fiber, but not necessarily to become the standard for the whole of the industry to adapt

[stormur]

BSA in CF frames maybe are not time consuming, like still (???) technological issue . It require extreme accuracy in molding/more it's gluing/ alu shell to CF BB - with proper insulation against galvanic corrosion , with glue which will resist applied forces for a long time. Next thing is thermal reactivity- different for CF and Alu what CAN ( but not have to ) cause troubles. Again "glue" is the key factor here.

Cannondale, Look; Ridley & Bianchi ( just for an example ) manage to do it , many others… well…. It's easier to overbuild a bit Bb area and mill shells to desired standard,or even mold tube with it, but still some even pricey frames has accuracy below any acceptance level.

[fromtrektocolnago]

I agree with the previous post that a bsa is time consuming. Bicycles are a business and everthing the majors do is about producing a bike more quickly and for less money. That explains the production move to Asia and the move away from BSA.

[Samuel Sanchez Gonzalez]

Asian open mould still offers BSA though

[djwalker]

I think that a good compromise is a PF frame and a BB like the Praxis conversion BB- the frame is quick, easy, and cheap to build and the BB is machined to be straight and also wedges into the frame. This eliminates the creaking and premature wear.

[Marin]

Yeah, and if alu/carbon was such an insurmountable problem, why aren't dropout dropping out left and right?

[stormur]

Different size of alu-cf connection, and completely different amount of forces applied to bonded surfaces.

However it's not uncommon , specially rear ones.

[Valbrona]

There is something critical to the good functioning of a bottom bracket. A BB shell with straight-cut faces which are perfectly parallel to one another makes for good alignment. And you cannot easily face a large diameter press-fit style bottom bracket shell.

[Calnago]

That's an excellent point @Valbrona, and one I should have made in my earlier post. It is absolutely critical that the bearings on each side be perfectly aligned with each other. Some systems, like the Praxis Works for example (there are others that work similarly) will have the two sides connected via threaded sleeve which expands against the bottom bracket shell, thus helping to ensure both good alignment and a tight fit within the shell to eliminate movement, without which often results in the creaking you hear.

[sawyer]

calnago - good post further up the thread

press fit looks better and has a stiffness increase that is immeasurably better, or maybe not, from an efficiency point of view

that's it